Stabilized diazotype photoprinting materials



Patented Mar. 4, 1947 UNITED STATES PATENT OFFICE Maximilian K. Reichel,Easton, Ia'.., assignor to General Aniline & Film Corporation, New York,

N. Y., a corporation of Delaware No Drawing. Application January 4,1945,

' Serial No. 571,352,

6 Claims.

This invention relates to the stabilization of photo-printing materialshaving light sensitive layers which are produced by the incorporation ofa diazo compound as the light-sensitive medium onto the surface of asuitable carrier base. More particularly, it refers to the stabilizationof so-called dry-development diazotype light-sensitive layers whereinthe diazo compound is incorporated into the light sensitive layertogether with an azo dyestufi coupling component. As diazo compounds forsuch dry-development or two-component diazotype light-sensitive layers,the most suitable have been found to be those which are derived fromorthoor para-aminonaphthols or aromatic paradiamines, particularlyN-monoor di-substituted aromatic paradiamines.

Various processes are known for the preparation of light-sensitivelayers which depend upon the use of a diazo compound as thelight-sensitive medium, and various materials have been employed for thecarrier of the light-sensitive layer, including textiles, paper,cellulosic films, and glass and metal surfaces. The sensitized carrieris exposed to light under a transparent original which it is desired toreproduce and the diazo compound is decomposed in the areas unprotectedby the outline of the original. The undecomposed diazo compound in theprotected areas is then used to develop'the image of the original bycoupling the said diazo compound in an alkaline atmosphere with an azodyestuff coupling component.

In the two-component layers which contemplate the incorporation of thecoupling component into the light-sensitive layer with the diazocompound, the development of the dyestuff forming the image is effectedby bringing the exposed light-sensitive layer into contact with gaseousammonia. This is known as the dry developing process. The dyestuifcomponents, as applied on the carrier are relatively unstable and cannotbe stored for long periods prior to use. The lightsensitive layers whichcarry the coupling component as well as the diazo compound in thelight-sensitive layer are subject to premature coupling of the saiddyestuif components as well as decomposition of the diazo compound uponlong storage.

Many attempts have been made to obtain more stable coating solutions andto render the lightsensitive layers produced therefrom less sensitive todeterioration without impairing the lightsensitive qualities of thediazo compound upon which the production of accurate images from the 30bilizers.

2 original depends. These attempts have hitherto been relativelyunsuccessful. It is therefore the object of this invention to providecoating solutions and light-sensitive layers, using diazo com- 5 poundsas the light-sensitive medium which can be stored for long periods priorto use and will be stable during storage, even under unfavorableconditions.

I have found that coating solutions and the light-sensitive layersprepared therefrom can be l5 ortho-hydroxy-carboxylic acids of thebenzene or naphthalene series. 7

Examples of such compounds are:

5-sulf0-Salicy1ic acid B-sulfo-o-cresotic acid6-su1fo-2hydroxy-3-naphtha1ene-carboxylic acid8-sulfo-2-hydroxy-3-naphtha1ene-carboxylic acid Diazotypelight-sensitive layers which have been stabilized by addition ofcompounds of the above classshow greatly improved keeping qualities andare stable against decomposition or deterioration for much longerperiods of storage than hitherto possible when using the same diazolight-sensitive compositions without these sta- The following examplesillustratethe invention but they are not intended to limit it thereto.The parts are by weight unless otherwise stated.

Example 1 A coating solution (A) was made up as follows:

were dissolved in 100 cc. of water. Another coating solution (B) wasmade up containing the same ingredients as in (A) except that partscitric acid and 44 parts 5-sulio-salicylic acid were substituted for the100 parts of citric acid. These solutions were then separately spread onstrips 59' of paper, fabric, and film by the usual coating,

method for the production of diazo-type lightsensitive layers, using adoctor blade to insure a thin even coating. After storage at roomtemperature for several months, the stability of the sensitizedmaterials of A and B was tested by example, is superior to that of thesample which does not contain the 5-sulfo-salicylic light-sensitivelayer.

Example 2 The composition of the coating solutions A and B was the sameas in Example 1, but as a stabilizer 47 parts 5-sulfo-o-cresotic acidper liter were used instead of the 5-sulfo-salicylic acid. The coatingsof A and B and the storage and test ing procedures were the same as inExample 1. The stability of the coating. made according to this examplewas found to be superior to that of the coating made from a solution notcontainacid in the ing 5-sulfo-o-cresotic acid as a stabilizer.

Erample 3 The composition of the coating solutions A and B was the sameas in Example 1, but as a stabilizer 53.5 parts of8-sulfo-2-hydroxy-3-naphthalene-carboxylic acid per liter were usedinstead of the 5-sulfo-salicylic acid. The coating,

storage, and testing procedures were the same as in Example 1. Thestability of the coating made according to this example was found to besuperior to that of the coating made from solution A not containing,8-sulfo 2 hydroxy-3-naphthalene-carboxylic acid as a stabilizer.

, Example 4 A coating solution was made up as follows:

i V V 7 Parts Zinc chloride double salt of the diazo compound obtainedfrom N,N-dimethy1-p-,

phenylenediamine 12.5 Citric acid 100 2,3-dihydroxy-naphthalene 5.9Thiourea 45.0

Sodium salt of the naphthalene-1,3,6-trisulfonic acid Aluminum sulfatewere d ssolved in 1000 cc. of water (solution A) Another coatingsolution (B) was made up containing the same ingredients as in solution(A). except that ,50 parts citric acid and 44 parts of 5-sulfo-salicylicacid were substituted for the 100 partsiof citric acid. Solutions A andB were then separately spread on strips of paper, fabric, and film bythe usual coating method in the same manner as described in Example 1.The lightsensitive layer thus produced was then stored at roomtemperature for several months and its stability then tested byobserving the appearance of color in the light-sensitive layer due topremature coupling of the dye components and by comparison of itslight-sensitive qualities with those of a testsample prepared andtreated in the same manner as the light-sensitive layer of this example.but omitting the 5-sulfo-salicylic acid as a stabilizer. When so tested,it was found that the light-sensitive layer made in accordance withlight-sensitive layers.

this example shows no discoloration due to premature coupling of the dyecomponents after the storage period, whereas, the light-sensitive layernot having the 5-sulfo-salicylic acid as a stabilizing agent, under thesame conditions, shows a' considerable amount of coloring, due to premavture coupling.

Example 5 Example 6 A coating solution was made up as follows:

- Parts Zinc chloride double salt of the diazo compound obtained from N,N-diethyl-p-phenylene-diamine 14 Citric acid1-phenyl-3-methyl-pyrazolone 8 Thiourea 45 were dissolved in 1000 cc. ofwater (solution A) Another coating solution (B) was made up containingthe same ingredients as in solution A except that 50 parts of citricacid and 47 parts of 5-sulfo-o-cresotic acid were substituted for the100 parts of citric acid. Solutions A and Bare then separately spread onstrips of paper, fabric, and film by the usual coating method in thesame manner as described in Example 1. The lightsensitive layer thusproduced was then stored at room temperature for several months and itsstability then tested in the same manner as in Example 1. The stabilityof the coating made according to this example was found to be superiorto that of the coating made from a solution (A),

-' not containing 5-sulfo-o-cresotic acid.

Example 7 A coating solution was made up as follows:

Parts 2.1 diazo-hydroxy-naphthalene-5-sulfonic acid 14.0 Citric acid 100Nickel sulfat 31.5 Phloroglucine 4.9 Thiourea 20.0

were dissolved in 1000 cc. of water (solution A). Another coatingsolution (B) was made up containing the same ingredients except that 50parts of citric acid and 47 parts of 5-su1fo-o-cresotic acid weresubstituted for the 100 parts of citric acid. These solutions are thenseparately spread on strips of paper, fabric, and film by the-usualcoating method, for the production of diazo-type The storage and testingprocedures were the same as in Example 1. The stability of the coatingsmade according to this example were found to be superior to that of theycoating made from solution A not containing 5- sulfo-o-cresotic acids asa stabilizer.

Example 8 lene carboxylic acid per liter were used instead of the5-sulfo-o-cresotic acid. The coating, storage and testing procedures arethe same as in Example 1. The stability of the coating made according tothis example was found to be superior to that of the coating made fromsolution A not containing 6-sulfo-2-hydroxy 3 naphthalenecarboxylic acidas a stabilizer.

Having now fully described my invention and having set forth the bestmanner in which to practice it, What I claim as new is:

1. Photoprinting materials comprising light sensitive layers on asuitable base containing in the light-sensitive layer a diazo compoundsuitable for forming a stable two-component diazotype layer, an azo dyecoupling component and a member of the class consisting of sulfonatedortho-hydroxy-carboxylic acids of the benzene and naphthalene series.

2. Photoprinting materials comprising lightsensitive layers on asuitable base containing in the light-sensitive layer a diazo compoundderived from an aromatic paradiaminean azo dye coupling component and amember of the class consisting of sulfonated ortho-hydroxy-carboxylicacids of the benzene and naphthalene series.

3. Photoprinting materials comprising lightsensitive layers on asuitable base containing in the light-sensitive layer a diazo compoundderived from an ortho-aminonaphthol compound, an azo dye couplingcomponent and a member of 6 the class consisting of sulfonatedortho-hydroxycarboxylic acids of the benzene and naphthalene series.

4. Photoprinting materials comprising lightsensitive layers on asuitable base containing in the light-sensitive layer a diazo compoundderived from an aromatic paradiamine, an azo dye coupling component and5-sulfo-salicylic acid.

5. Photoprinting materials comprising lightsensitive layers on asuitable base containing in the light sensitive layer a diazo compoundderived from an aromatic paradiamine, an azo dye coupling component and8-sulfo-2-hydroxy-3- naphthalene-carboxylic acid.

6. Photoprinting materials comprising lightsensitive layers on asuitable base containing in the light-sensitive layer, a diazo compoundderived from an ortho-aminonaphthol compound, an azo dye couplingcomponent and 5-su1fo-ocresotic acid.

MAXIMILIAN K. REICHEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Schmidt et a1. Feb. 16, 1932

